Fuel cell system

Abstract

A fuel cell system includes: a fuel cell stack; an oxygen tank; an oxygen pipe connecting the fuel cell stack and the oxygen tank; an oxygen regulator disposed in the oxygen pipe and configured to regulate a flow rate of oxygen to be supplied from the oxygen tank to a cathode of the fuel cell stack; an oxygen stop valve disposed in the oxygen pipe; and a controller configured to execute, when activating or stopping the fuel cell stack: a first process of opening the oxygen stop valve and the oxygen regulator; a second process of closing the oxygen stop valve and the oxygen regulator when a cathode internal pressure reaches a predetermined first cathode pressure; and a third process of outputting a signal indicating occurrence of oxygen leakage when the cathode internal pressure after a predetermined period is lower than a predetermined second cathode pressure.

What is claimed is: 
     
         1 . A fuel cell system comprising:
 a fuel cell stack;   an oxygen tank;   an oxygen pipe connecting the fuel cell stack and the oxygen tank;   an oxygen regulator disposed in the oxygen pipe and configured to regulate a flow rate of oxygen to be supplied from the oxygen tank to a cathode of the fuel cell stack;   an oxygen stop valve disposed in the oxygen pipe; and   a controller, wherein   the controller is configured to execute, when activating or stopping the fuel cell stack:
 a first process of opening the oxygen stop valve and the oxygen regulator; 
 a second process of closing the oxygen stop valve and the oxygen regulator when a cathode internal pressure of the fuel cell stack reaches a predetermined first cathode pressure; and 
 a third process of outputting a signal indicating occurrence of oxygen leakage when the cathode internal pressure after a predetermined period is lower than a predetermined second cathode pressure. 
   
     
     
         2 . The fuel cell system according to  claim 1 , further comprising:
 an oxygen tank valve attached to the oxygen pipe between the oxygen stop valve and the oxygen tank; and   an exhaust oxygen valve configured to stop discharge of gas from a cathode gas outlet of the fuel cell stack, wherein   the controller is configured to, when stopping the fuel cell stack,
 before execution of the first process, the second process, and the third process, open the oxygen tank valve, the oxygen stop valve, the oxygen regulator, and the exhaust oxygen valve so as to discharge water remaining in the cathode from the fuel cell stack, and 
 close the oxygen stop valve and the exhaust oxygen valve and, when an internal pressure of the oxygen pipe on an upstream side of the oxygen stop valve reaches an upper limit cathode pressure higher than the predetermined first cathode pressure, close the oxygen tank valve. 
   
     
     
         3 . The fuel cell system according to  claim 2 , further comprising an exhaust oxygen pipe connected to the cathode gas outlet, wherein the exhaust oxygen valve is provided in the exhaust oxygen pipe. 
     
     
         4 . The fuel cell system according to  claim 1 , wherein the controller is configured to, when activating or stopping the fuel cell stack, output the signal indicating the occurrence of the oxygen leakage in a case where the cathode internal pressure after the predetermined period is not lower than the predetermined second cathode pressure and an amount of decrease in an internal pressure of the oxygen pipe on an upstream side of the oxygen stop valve during the predetermined period is larger than a permissible decrease amount. 
     
     
         5 . The fuel cell system according to  claim 1 , further comprising a first pressure sensor provided in the oxygen pipe on a downstream side of the oxygen stop valve and configured to measure the cathode internal pressure, wherein the controller is configured to acquire the measured cathode internal pressure from the first pressure sensor. 
     
     
         6 . The fuel cell system according to  claim 2 , further comprising a second pressure sensor provided in the oxygen pipe on the upstream side of the oxygen stop valve and configured to measure the internal pressure of the oxygen pipe on the upstream side of the oxygen stop valve, wherein the controller is configured to acquire the measured internal pressure from the second pressure sensor.